Here's the build I've been running lately on my ranger, and I absolutely love it in the Competition Arenas:
R/anything
Expertise: 11+1+2
Marksmanship: 10+1
Wilderness Survival: 8+1
Beast Mastery: 6+1
Expertise: 11 + 1 + 2
Marksmanship: 10+1
Wilderness Survival: 8+1
Beast Mastery: 6+1
Equipment:
Runes: Major Expertise, Minor Marksmanship, Minor Wilderness Survival, Minor Beast Mastery
Mask: Hunter's Mask (+1 to Expertise)
Armor set: Preferrably Druid's, but not required
Weapon: Shortbow/Half-moon (with a Zealous string if you want more energy gain)
Punishing Shot {E}
Kindle/Ignite Arrows
Distracting Shot
Tiger's Fury
Whirling Defense
Pin Down*
Troll Unguent
Resurrection Signet
*Keep a bow with at least an 80 meter range on switch for pinning down a chasing enemy warrior or a running caster.
Kindle Arrows adds around 16 damage to each arrow, which adds up very quickly when you throw in the occasional bonus damage from Punishing Shot and the rapid speed of your attacks. The only setup that shoots faster than TF using a shortbow/halfmoon is a Quick Shot build, which, for many reasons I'll list if you ask, I would avoid if at all possible). Although this damage isn't the sort of spike you can expect from an air elementalist or mesmer Fragility build, it's enough damage with enough speed to take down an enemy fairly quickly on your own.
Use Punishing Shot and Distracting Shot to make enemy casters mad (though monks can be a bit of a challenge due to their quick casting skills), use Tiger's Fury to make your damage and your interrupts MUCH quicker (with an 8 second duration and a 10 second recharge, might I add). If that enemy mesmer is about to land Empathy on you, give him a Punishing/Distracting shot and make him pay for it. Having an air spiker elementalist alt, i know it's extremely annoying to be interrupted on my exhaustion-causing, big damage spells like Lightning Surge (both with 2 second cast times and easily interrupted by this build), or to have my lightning orb interrupted/disabled. Use Pin Down if they start to get low on health, just in case.
So, that takes care of casters, but what about warriors/other rangers? The stance "Whirling Defenses" provides just about as good of a defense as any. Some people would choose Throw Dirt instead, but I like Defenses because it has a longer duration than Throw Dirt and allows you to dodge arrows, while Throw Dirt only puts the adjacent melee opponents out of comission. Using Whirling Defenses makes you block 75% of attacks, but it feels like 90%, since your health almost never goes down while it's up. That said, you're basically immune to interrupts from anyone other than spellcasters, so go ahead and use Troll Unguent and heal up while you're still tanking, or Pin Down that warrior/ranger on you and run.
You're welcome to switch out Distracting Shot for Concussion Shot if you so desire, or Pin Down for Throw Dirt if you want to have a lot of defense against a warrior.
Oh, BTW, you might not want to use Oath Shot as your elite if you're going to be a trapper. As soon as you use Oath Shot, you're going to get aggro from whatever you shot, meaning you can't trap again till they're dead. Bring Spiked Trap or maybe Barrage to finish off whatever doesn't get owned by your trap.
